For instance, U.S. Pat. No. 6,129,245 disclosed a “WASHING SYSTEM WITH AUXILIARY RESERVOIR” having a plurality of dispensers, a first collapsible container, a second collapsible container, at least one connecting tube and a supply line. Each dispenser includes a pump having an inlet and an outlet. The first collapsible container is used for containing liquid cleanser, and provided with an outlet. The second collapsible container is used for containing the liquid cleanser and provided with an outlet, the first collapsible container being located above the second collapsible container. The connecting tube is used for communicating the outlet of the first collapsible container with that of the second collapsible container. The supply line is used for communicating the liquid cleanser inside the first collapsible container and the second collapsible container to the plurality of dispensers, so as to permit the flow of liquid cleanser to the dispenser first from the first collapsible container, and then alternatively from the second collapsible container after the liquid cleanser inside the first collapsible container is consumed.
Further, for example, U.S. Pat. No. 7,364,053, entitled “SINK SIDE TOUCHLESS FOAM DISPENSER” and U.S. Pat. No. 7,455,197, entitled “SINK SIDE TOUCHLESS FOAM DISPENSER NOZZLE ASSEMBLY” disclosed a storage compartment used for storing liquid cleanser under the countertop, respectively, delivering the liquid cleanser stored inside the storage compartment to a plurality of dispensers on the countertop through a conduit through a plurality of liquid pumps, such that the liquid cleanser may be discharged via the plurality of dispensers.
Moreover, published U.S. Patent Application No. 2017027390, entitled “AUTOMATIC FOAM SOAP DISPENSER”, disclosed a reservoir used for storing liquid cleanser under the countertop, and coupled with a plurality of dispensers on the countertop through piping. Each dispenser is provided therein with a sensor, a motor and a pump, so as to discharge the liquid cleanser via an outlet of the dispenser through the piping through the motor and the pump.
Further, for example, U.S. Pat. No. 5,540,362, entitled “LIQUID SOAP SUPPLYING DEVICE”, disclosed a tank for storing liquid soap. The liquid soap is provided for a plurality of nozzles by the tank through a liquid soap supplying pipe. The tank is provided therein with a remaining volume sensor having five-staged contact points in the tank. Moreover, the remaining volume of liquid soap in the tank is recognized by a control part, while a buzzer is controlled by the control part, in such a way that a ring for a specified period of time is used by the remaining volume sensor for cuing when the uppermost level of the remaining volume of liquid soap is reached.
All the above-mentioned patents disclosed the use of the storage for storing the liquid cleanser provided for the plurality of dispensers on the countertop to dispense soap. In all of these patents, however, it is necessary to supply soap on the countertop in the process of supplement of liquid cleanser. Thus, it is apt to spill the liquid cleanser carelessly due to space limitation, with the dirty and disordered under the countertop. Moreover, it is impossible to perceive the content inside the storage from the outside. In general, the consumption of liquid cleanser and the requirement for supplement may be not alerted until the dispenser is incapable of supplying the liquid cleanser. Otherwise, it is necessary for the cleaning staff to inspect the content of the storage at irregular intervals so as to supply the liquid cleanser timely. In this way, working efficiency of the cleaning staff is impacted.